Anti-rotation device for a steerable rotary drilling device

Abstract

In a drilling apparatus of the type comprising a rotatable drilling shaft and a housing for rotatably supporting a length of the drilling shaft for rotation therein, a rotation restraining device associated with the housing for restraining rotation of the housing. In one embodiment, the rotation restraining device is comprised of at least one roller on the housing, the roller having an axis of rotation substantially perpendicular to a longitudinal axis of the housing and being oriented such that it is capable of rolling about its axis of rotation in response to a force exerted on the roller substantially in the direction of the longitudinal axis of the housing. In a further embodiment, the rotation restraining device is comprised of at least one piston on the housing.

Description

FIELD OF INVENTION[0001]The present invention relates to a steerable rotary drilling device and a method for directional drilling using a rotary drilling string. Further, the present invention relates to a drilling direction control device and a method for controlling the direction of rotary drilling. As well, the invention relates to a rotation restraining device or an anti-rotation device for use with a steerable rotary drilling device or a drilling direction control device.BACKGROUND OF INVENTION[0002]Directional drilling involves varying or controlling the direction of a wellbore as it is being drilled. Usually the goal of directional drilling is to reach or maintain a position within a target subterranean destination or formation with the drilling string. For instance, the drilling direction may be controlled to direct the wellbore towards a desired target destination, to control the wellbore horizontally to maintain it within a desired payzone or to correct for unwanted or und...

AI Technical Summary

Benefits of technology

[0040]The distal radial bearing may be comprised of any bearing, bushing or similar device which is capable of radially and rotatably supporting the drilling shaft while transmitting the effects of deflection of the drilling shaft past the distal radial bearing. For example, the distal radial bearing may allow for radial displacement of the drilling shaft. Preferably, however, the distal radial bearing is comprised of a fulcrum bearing which facilitates pivoting of the drilling shaft at the distal radial bearing location.

[0144]The orienting step may be comprised of communicating the desired orientation of the drilling string directly from the surface of the wellbore to the drilling direction control device either with or without manipulating the drilling string. Preferably, however, the orienting step is comprised of comparing a current orientation of the drilling string with the desired orientation of the drilling string and rotating the drilling string to eliminate any discrepancy between the current orientation and the desired orientation. Once the desired orientation of the drilling string is achieved by manipulation of the drilling string, the desired orientation may then be communicated to the drilling direction control device either directly from the surface of the wellbore or from a drilling string orientation sensor located somewhere on the drilling string.

Problems solved by technology

However, various problems are often encountered with sliding drilling.

As well, the downhole motor tends to be subject to wear given the traditional, elastomer motor power section.

Furthermore, since the drilling string is not rotated during sliding drilling, it is prone to sticking in the wellbore, particularly as the angle of deflection of the wellbore from the vertical increases, resulting in reduced rates of penetration of the drilling bit.

Other traditional problems related to sliding drilling include stick-slip, whirling, differential sticking and drag problems.

For these reasons, and due to the relatively high cost of sliding drilling, this technique is not typically used in directional drilling except where a change in direction is to be effected.

However, rotary drilling tends to provide relatively limited control over the direction or orientation of the resulting wellbore as compared to sliding drilling, particularly in extended-reach wells.

Although the use of a combination of sliding and rotary drilling may permit satisfactory control over the direction of the wellbore, the problems and disadvantages associated with sliding drilling are still encountered.

However, none of these attempts have provided a fully satisfactory solution.

As a result, it has been found that the drilling string may be exposed to excessive bending stress.

However, it has been found that the use of a flexible or articulated shaft to avoid the generation of excessive bending force on the drilling string may not be preferred.

Specifically, it has been found that the articulations of the flexible or articulated shaft may be prone to failure.

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